The invention relates to a method of manufacturing an electron gun which is centered along an axis, a support of electrically insulating material and an electrode having a plate-shaped fastening member, which at a free end partly surround an aperture, being attached to each other, the support being softened, and the fastening member being introduced, at least partly, into the softened support along a direction of penetration, after which the assembly is cooled.
A method of the type described in the opening paragraph is known from U.S. Pat. No. 4,096,408. This Application describes a method of manufacturing an electron gun, in which in one step of the method electrodes and rod-like glass bodies are attached to each other by softening the rod-like glass bodies by raising the temperature, after which the glass bodies are pressed onto the fastening members, such that the material of the glass bodies surrounds a part of these fastening members, after which the assembly is left to cool down. The electrodes of U.S. Pat. No. 4,096,408 are each provided with two pairs of relatively small fastening members. The free ends of the fastening members described in U.S. Pat. No. 4,096,408 may partly surround an aperture, as shown in FIG. 7 of this Patent.
One important aspect for the quality of an electron gun is its sensitivity to vibrations, the so-called microphonic behaviour. Vibrations may be caused by external influences, for example by sound vibrations which are transmitted to the electron gun or they may be caused by processes taking place inside the electron gun, for example, changing electric voltages between electrodes, which changing voltages lead to changing forces on the electrode components. Vibrations disturb the relative position of the electrodes, subjecting the position and the intensity of the electron beam generated by the electron gun to time-dependent changes. As a consequence displays of the electron beam on, for example, a picture screen of a cathode ray tube are subject to time-dependent changes which adversely affects picture quality. In this respect it is of particular significance that the relative positions of the electrodes are disturbed by vibrations along the axis of the electron gun.